Project Brief

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Striga (witchweed) is a parasitic weed that seriously constrains the productivity of staples such as maize, sorghum, millet and upland rice in Sub-Saharan Africa. The weed survives by siphoning off water and nutrients from the crops for its own growth. It causes serious damage to its host crop before emerging from the soil by producing phytotoxins which are harmful to the host crop. Upon attachment to host roots, it withdraws photosynthate, minerals and water, resulting in characteristic “witch” appearance of the host crop manifested by stunting and withering. Striga infests as much as 40 million hectares of smallholder farmland in the region and causes yield losses ranging from 20–80% and even total crop failure in severe infestation. Striga seeds remain dormant and viable in the soil for up to 20 years. With every planting season, some of the dormant seeds, stimulated by crop exudates, germinate and infest the host crop while reproducing and increasing the Striga seeds in the soil thus escalating the problem. AATF is collaborating in a public/private sector partnership project to promote technological interventions for the control of Striga in maize in Africa.

To enable smallholder farmers in Sub-Saharan Africa have access to appropriate Striga management technologies such as seed of Imazapyr-resistant (IR) maize, Striga tolerant varieties, suppression and trap cropping management systems and soil fertility management.

The problem
The damage caused annually by Striga in Sub-Saharan Africa is estimated at US$ 1 billion, aff ecting the livelihoods of more than 100 million people. Fifteen countries of eastern, southern and western Africa account for 95% of the continent’s Striga infested fi elds.

The solution
The product combines a low-dose Imazapyr seed coating applied to Imazapyrresistant (IR) maize seed. Small quantities of Imazapyr (as little as 30 g/ha) act before or at the time of Striga attachment to the maize root and so prevent the phytotoxic eff ect of Striga on the maize plant, thus enabling the plant to grow to its full potential. Additionally, Imazapyr that is not absorbed by the maize seedling diff uses into the surrounding soil and kills ungerminated Striga seeds. This technology for controlling Striga is referred to as STRIGAWAY® technology. The low-dose herbicide seed dressing used in the STRIGAWAY® technology controls Striga without impacting sensitive intercrops when planted 10cm away from the maize hills. This allows smallholder farmers who practice intercropping to incorporate this technology in their farming systems. In deployment of Striga management technologies, AATF encourages farmers to incorporate soil fertility practices such as use of legume rotation and intercrops and fertiliser additions to replenish soil nutrients and optimise crop yields.

The use of IR-Maize technology to control Striga leads to yields 38–82% higher than those currently obtained from traditional maize varieties. In Kenya, a conservative estimate indicates that when adopted, the proposed technology will lead to an extra 62,000 tonnes of maize in Western Province alone. This translates to US$ 5.3 million per year using the 2002 estimates of farm-gate price for maize in Kenya.
Better tools, better harvests, better lives

AATF interventions

  • Facilitating negotiations for release of herbicide-resistant maize seed
  • Development and implementation of a technology stewardship plan focused on seed stockists and maize farmers
  • Facilitate testing of improved soil fertility management solutions
  • Facilitating herbicide registration process
  • Facilitating baseline studies to benchmark Striga incidences and adoption studies to evaluate technology uptake and use

Partner institutions


  • CIMMYT – International Maize and Wheat Improvement Centre
  • BASF – A private chemical company
  • Weizmann Institute of Science, Israel
  • TSBF-CIAT – Tropical Soil Biology and Fertility Program of the International Centre for Tropical Agriculture
  • IITA – International Institute of Tropical Agriculture


  • KARI – Kenya Agricultural Research Institute
  • Ministry of Agriculture
  • WeRATE – The Western Regional Alliance for Technology Evaluation: A consortium of NGOs, community based organisations and farmers’ organisations
  • Local private seed companies – Western Seed, Lagrotech and Kenya Seed


  • NARO – National Agricultural Research Organisation
    FICA – Farm Inputs Care Centre Ltd
  • Africa 2000 Network
  • NAADS – National Agricultural Advisory Services


  • Ministry of Agriculture
  • Tanseed International Ltd
  • ARI – Agricultural Research Institute, Mwanza


  • University of Malawi, Bunda College
  • Zum Seed Ltd
  • Ministry of Agriculture
  • Chitedze Research Station

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